Paraxylene is a valuable chemical intermediate used in the production of terephthalic acid, which in turn is used in the production of polymers such as polytrimethyleneterephthalate (PTT), polybutyleneterephthalate (PBT) and polyethyleneterephthalate (PET). Given the large market for PET plastics and fibers, in addition to other end products produced from paraxylene, there is a substantial demand for paraxylene in high purity.
Catalytic reforming generally refers to the conversion (or “aromatization”) of a naphtha hydrocarbon feed, as a crude oil fraction, to the major products of benzene, toluene, and the xylene isomers. To maximize paraxylene production by utilizing the aromatic compounds from the reforming process, the shortage of available methyl groups must be addressed. The integration of aromatic methylation with transalkylation addresses this issue, and is an effective means to increase methyl groups on aromatic ring and maximize the production of mixed xylenes and paraxylene. Furthermore, by increasing the methylation of the aromatic compounds of the feed stream, the benzene production can be minimized or eliminated.